petrol leak !!!!

[tillett22]

Hi all, I am after a bit of advice.

I have recently brought my first vfr 400 and while out for a ride i noticed when stopped having a cup of tea, that i could see a tiny drip of petrol coming from the petrol tap on the right side of the bike.

Under further investigation I have found out it only leaks when the bike has stopped running and the fuel tap is left on. It doesn't do it when the bike is running. Its leaking from a small outlet on the tap next to the vent pipe.

[bikemonkey]

Sounds to me like your tap may have been modded.

Easy way round it is just remember to turn it off when not using it, or you could fix it properly with a tap repair kit from Rick Oliver.

[speedy231278]

It shouldn't leak when left 'on' even if it's been modded as per HRC (like mine). Best guess is that a seal is leaking somewhere. There isn't a vent pipe as such on the fuel tap, there are three spigots on it. The biggest one, facing forwards, is obviously the fuel pipe that goes to the carbs. There's a smaller one facing forwards that in unmodified condition will have a vacuum pipe on it that is linked to one of the engine inlet tracts, and is used to operated the fuel tap diaphragm. A third one faces downward, and usually has nothing attached. I believe this is used to let the diaphragm 'breathe'. If fuel is coming out of this one, or the vac one if there's no tube attached, then something has gone wrong inside the fuel tap and it is leaking, so you should either source a spare one, or take this one off the bike to investigate further. You don't want your drip to turn into a flood for obvious reasons!

[tillett22]

It is the third one facing down that's leaking. What do you mean mod? I am going to drain off the fuel and remove the tank and have a look. Would a RO seal kit fix it? I don't want my bike turning into a ball of flames

[CMSMJ1]

the outer spigot is a drain - so it does sound buggered

[Neosophist]

You can think of the Honda fuel tap as an automatic fuel tap within the tap.

In other words, even if you have the tap switched to the On position, if you pull the pipe off fuel will not come out unless the engine is running.

There is a diaphram inside the tap that gets opened by the suck from the engine that lets fuel flow.

If fuel is leaking then there is a chance there is a hole in the diaphram somewhere. The tap is simple to strip so get it off and check it.

Sometimes people bypass the vaccum diaphram by removing the spring and stopping it operating, turning the fuel tap into a standard design and bypassing the Honda safety feature.

If it hasnt been modified then while investigating / repairing the tap, it is also a good time to replace the small vaccum hose that runs to the bike at the same time

[phil x]

Hi Graham, it's Phil here.

Sorry to hear that you have drips of petrol.
When I bought the bike, the tap was "always on", I stripped the tap & recall finding a bit of rubber (maybe a slither of O ring?) The tap worked perfectly for me thereafter. It was standard with no holes in the diaphragm that I was aware of. I ALWAYS turned the tap off after a ride from then on purely for peace of mind.

At no point did I ever notice or suspect fuel dripping from the tap after being parked up during a ride.
One of the small spigots has a very short piece of vac pipe over the end. This is to prevent the actual vacuum pipe from being mistakenly fitted to the wrong spigot.

Phil

I hope that you get sorted easily

[tillett22]

Thanks all for your advice. I will have a over the next few days.

Phil, no worries just one of them things, i did see the small piece of pipe and wonder. Did you replace the vacuum pipe?

[phil x]

Thanks all for your advice. I will have a over the next few days.

Phil, no worries just one of them things, i did see the small piece of pipe and wonder. Did you replace the vacuum pipe?

Yep, the vacuum pipe is the thick walled item from Rick O.
A bit puzzled with the fuel leak, unless there is a pin prick hole in the diaphragm, I did carefully check it when I had the tap split & all looked perfect.

I do feel a bit bad as I sold the bike as being mechanically spot on & don't want to see you having problemsuy

[tillett22]

Well got in last night and removed tank and removed the fuel tap for further inspection. Nothing too big to report, but a few small bits in the seals but new RO fuel tap kit on its way. I don't fancy turning into phelix of flames.